Book excerpt: A superconducting magnetic-energy-storage (SMES) unit is suitable for power-system stabilization because it can provide positive damping by absorbing or releasing energy with a relatively fast response time, 10 ms. In the fall of 1982, an SMES unit was installed at the Tacoma Substation of the Bonneville Power Administration as an experiment in monitoring, predicting and improving system stability. This paper reports principally on the system testing.